1. Field of the Invention
The present invention relates to a heat-processing method and apparatus for a semiconductor process, which are used for subjecting a plurality of target substrates to a heat process under a vacuum pressure. The term “semiconductor process” used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or a glass substrate used for an LCD (Liquid Crystal Display) or FPD (Flat Panel Display), by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
2. Description of the Related Art
In manufacturing semiconductor devices, heat-processing apparatuses are used for performing heat processes, such as CVD (Chemical Vapor Deposition) and oxidation, on a target substrate, such as a semiconductor wafer. For example, where a vertical heat-processing apparatus of the batch type is used as a heat-processing apparatus, a heat process is performed, as follows.
At first, the interior of the reaction tube of the heat-processing apparatus is heated up (increase in temperature) by a heater to a predetermined load temperature, such as 400° C., and a wafer boat that holds a plurality of semiconductor wafers is loaded. Then, the interior of the reaction tube is heated to a predetermined process temperature, such as 800° C. Furthermore, gas within the reaction tube is exhausted through an exhaust port, so that the pressure in the reaction tube is reduced to a predetermined pressure, such as 53.2 Pa (0.4 Torr).
Then, the interior of the reaction tube is kept at the predetermined temperature and pressure (kept exhausted), a process gas is supplied through a process gas feed line into the reaction tube. For example, in the case of CVD, when a process gas is supplied into a reaction tube, the process gas causes a thermal reaction and thereby produces reaction products. The reaction products are deposited on the surface of a semiconductor wafer, and form a thin film on the surface of the semiconductor wafer.